The examination of puberty in male mammals, and its regulation by environmental variables has received relatively little experimental attention. A small number of species of temperate zone male rodents have been examined. In these animals nutritional, photoperiodic, and social variables have varying effects on various measures of sexual maturation. However, the vast majority of mammalian species evolved and still live in the tropics. Here, since environmental cues such as temperature and photoperiod are relatively invariant, the most likely regulators of puberty are food availability and social cues. Reproduction is an energetically demanding process, thus food availability and normal growth are critical for sexual maturation. Likewise, mate availability is important. Male maturation can be influenced by the presence, or absence of fertilizable females. Not only are these two variables of interest independent of each other, they also co-vary and undoubtedly modify the effects of each on puberty. I plan to use the male musk shrew (Suncus murinus), a tropical mammal to develop a model system in which to examine the effects of these two,interdependent, environmental cues on male sexual maturation. I will manipulate food and mate availability by restricting males' access to food and/or females. I will also determine the extent to which these two variables are related to influence each other. Unlike past work in this area I plan to examine several behavioral, physiological and hormonal aspects of puberty. This is important since some environmental variables may effect puberty via physiological versus psychological(behavioral) channels. The goal of this proposal is to develop a system in which the effects of both positive and negative environmental cues on male puberty can be assayed independently and dependently.